Chronic fatigue syndrome/Systemic exertion intolerance disease


Systemic exertion intolerance disease/chronic fatigue syndrome (SEID/CFS) is a long-term illness that affects many body systems. People with this illness are not able to do their usual activities. Sometimes, they may be confined to bed.

One common symptom is severe fatigue. It does not get better with rest and is not directly caused by other medical problems. Other symptoms can include problems with thinking and concentrating, pain, and dizziness.


The exact cause of SEID/CFS is unknown. It may have more than one cause. For example, two or more possible causes may work together to trigger the illness.

Researchers are looking into these possible causes:

Genetics or environmental factors may also play a role in the development of SEID/CFS:


There are three main, or "core," symptoms in people with SEID/CFS:

People with SEID/CFS have persistent and profound fatigue and are unable to do activities they were able to do before the illness. This extreme fatigue is:

SEID/CFS symptoms can become worse after physical or mental activity. This is called post-exertional malaise (PEM), also known as a crash, relapse, or collapse.

Sleep issues may include problems falling or staying asleep. A full-night's rest does not relieve fatigue and other symptoms.

People with SEID/CFS also often experience at least one of the two following symptoms:

Other common symptoms include:

Exams and Tests

The Centers for Disease Control (CDC) describes SEID/CFS as a distinct disorder with specific symptoms and physical signs. Diagnosis is based on ruling out other possible causes.

Your health care provider will try to rule out other possible causes of fatigue, including:

A diagnosis of SEID/CFS must include:

There are no specific tests to confirm the diagnosis of SEID/CFS. However, there have been reports of people with SEID/CFS having abnormal results on the following tests:


There is currently no cure for SEID/CFS. The goal of treatment is to relieve symptoms.

Treatment includes a combination of the following:

Some drugs can cause reactions or side effects that are worse than the original symptoms of the disease.

People with SEID/CFS are encouraged to maintain an active social life. Mild physical exercise may also be helpful. Your health care team will help you figure out how much activity you can do, and how to slowly increase your activity. Tips include:

Relaxation and stress-reduction techniques can help manage chronic (long-term) pain and fatigue. They are not used as the primary treatment for SEID/CFS. Relaxation techniques include:

It also may be helpful to work with a therapist to help you deal with your feelings and the impact of the illness on your life.

Newer medicine approaches are being researched.

Support Groups

Some people may benefit from taking part in an SEID/CFS support group.

Outlook (Prognosis)

The long-term outlook for people with SEID/CFS varies. It is hard to predict when symptoms first start. Some people completely recover after 6 months to a year.

About 1 in 4 people with SEID/CFS are so severely disabled that they can't get out of bed or leave their home. Symptoms can come and go in cycles, and even when people feel better, they may experience a relapse triggered by exertion or an unknown cause.

Some people never feel like they did before they developed SEID/CFS. Studies suggest that you are more likely to get better if you receive extensive rehabilitation.

Possible Complications

Complications may include:

When to Contact a Medical Professional

Call your provider if you have severe fatigue, with or without other symptoms of this disorder. Other more serious disorders can cause similar symptoms and should be ruled out.

Review Date: 4/12/2018
Reviewed By: Gordon A. Starkebaum, MD, ABIM Board Certified in Rheumatology, Seattle, WA. Internal review and update on 07/12/2019 by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

This information should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. © 1997- 2007 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.